1. Field of the Invention
This invention relates to a specimen collection container assembly and more particularly to a collection container for collecting biological fluid specimens where a small quantity of fluid may be collected and retained in the container while maintaining a container size sufficient to be easily accommodated and/or compatible with standard clinical equipment and instrumentation.
2. Description of Related Art
Blood samples and other biological fluid specimens are routinely taken and analyzed in hospital and clinical situations for various medical purposes. Collection, handling and testing of these samples typically requires the use of various medical testing instruments. As the blood and fluid specimens are usually collected in a standard sized collection tube, the medical instruments used to test the samples are designed to accommodate these standard sized collection tubes.
Conventional blood collection tubes used in most clinical situations are elongated cylindrical containers having one end closed by a semi-spherical or rounded portion and an opposed open end. The open end may be sealed by a resilient cap or stopper. The tube defines a collection interior which collects and holds the blood sample. The most common size of these blood collection tubes are designed to accommodate approximately 6-10 ml of blood or other biological fluid samples. Illustrative of such blood collection tubes is the VACUTAINER(copyright) brand blood collection tube sold by Becton, Dickinson and Company, 1 Becton Drive, Franklin Lakes, N.J. (registered trademark of Becton, Dickinson and Company).
A phlebotomist or other medical technician typically obtains a specimen of the patient""s blood in the tube by techniques well known in the art. The tube is then appropriately labeled and transferred from the site of collection to a laboratory or other location where the contents of the tube are analyzed. During collection and analysis the tube may be supported by various medical instruments. The plasma or serum derived therefrom is processed and analyzed either manually, semi-automatically or automatically. In some cases, the specimen must first be dispensed from the collection tube to a sample test tube or cuvette.
In certain situations it is only necessary to obtain a small quantity of blood or other biological fluid specimens. These situations may include pediatric, or geriatric patients and other instances where large blood samples are not required. Small quantities of blood cannot be easily collected in standard collection tubes as described above because the sample level in such containers would not be adequate for retrieval prior to analysis. Such small quantities of fluids also have a tendency to significantly evaporate when stored in larger containers, thus concentrating the chemical and enzymatic constituents therein. This may result in erroneous analytical results and could possibly affect the diagnosis and treatment given the patient. Therefore, it is desirable to employ small-volume containers which substantially inhibit evaporation for the storage and delivery of minute fluid samples in the laboratory.
Various specimen containers such as those incorporating a xe2x80x9cfalse bottomxe2x80x9d have been proposed to achieve decreased volume capacity in conjunction with standard external dimensions. However, these various specimen containers are not compatible with standard clinical equipment and instrumentation due to their design. In particular, these specimen containers have false bottoms with a generally flat, planar bottom end and a circular shaped opening.
Other specimen containers include partial-draw tubes which have standard external dimensions with partial evacuation so that blood fills only a portion of the internal volume. However, partial-draw tubes exhibit a reduction in the draw rate of a sample which reduces the collection efficiency of such tubes. In addition, partial-draw tubes may result in an inconsistent fill volume which may alter test results. Furthermore, it is difficult to determine accurate sample quantities with such partial-draw tubes because the slow rate of sample draw is not consistently measurable.
In clinical use, it is desirable for such specimen collection containers to have rounded bottom configurations that closely simulate a standard-sized blood collection tube configuration instead of planar bottoms. Rounded bottom configurations facilitate compatibility with clinical equipment and instrumentation.
Therefore there is a need to provide a specimen collection container assembly for collecting blood samples and other biological fluid specimens of relatively small volumes where the assembly may be accommodated and/or compatible with standard clinical equipment and/or instrumentation and where the integrity of the sample and specimens are maintained during draw, storage and transport.
The present invention is a collection assembly comprising a container. The container preferably comprises an open top portion, a bottom portion and a sidewall extending from the open top portion to the bottom portion. The bottom portion comprises a closed bottom end. The sidewall comprises an inner wall, an outer wall and a wall space between the inner and outer wall. Most preferably, the wall space is formed during the molding process of the tube whereby an inert gas is injected into the sidewall so that a large amount of material can be eliminated and the inert gas is subsequently removed or exhausted from the sidewall. Optionally, the assembly may further comprise a closure at the open top portion of the container.
Most preferably, the wall space occupies an area within the sidewall of the container so as to reduce the interior volume of the container thereby creating a false volume effect to the container.
The wall space of the sidewall of the container provides a false volume effect to the assembly, as well as allowing the container to be compatible with standard clinical equipment and instrumentation because the external dimensions of the container are about the same as a standard-sized or full draw blood collection container assembly.
In addition, the assembly may further comprise a closure such as a cap or a stopper at the open end of the container.
Most preferably, the assembly of the present invention can be either evacuated or non-evacuated. Desirably, the assembly is made from polyethylene terephthalate, polypropylene, polyethylene, polyethylene napthalate polyvinyl chloride or copolymers thereof.
The assembly of the present invention is preferably formed as follows:
(a) melting a polymer such as polyethylene terephthalate (PET) or polypropylene;
(b) injecting the melted polymer into an injection mold that has a mold cavity of between 2-64 cavities;
(c) molding the melted polymer into a container that comprises an open top portion, a bottom portion and sidewall extending from the open top portion to the bottom portion whereby the sidewall comprises an outer wall that is formed by the mold cavity and inner wall that is defined by the core. As the skilled artisan will appreciate, injection molding is a process that works by putting the polymer in molten form and injecting same into a mold. The mold is a hollowed out area that allows the polymer to take shape after curing;
(d) injecting an inert gas into the sidewall of the container by a so-called core pin method, as utilized in molding operations for gas assist molding. The core pin method is a process which hollows out the thickness of the wall areas by taking up volume with gas instead of plastic. Thereafter, the gas is allowed to escape, which creates the pocket.
(e) ejecting the inert gas from the sidewall whereby a space is created between the inner and outer sidewall, creating the false volume of the tube;
(f) curing the tube, which takes place during the time the gas is ejected from the mold. Preferably, the curing time is between 6-15 seconds; and
(g) ejecting the part from the mold by rods that push the part from the cavity.
An advantage of the assembly of the present invention is that it provides a full-draw blood collection container assembly having a reduced internal volume but with external dimensions that are approximately the same as a standard-sized blood collection container assembly. In addition, the assembly of the present invention has a standard draw rate as compared to partial draw rate tubes.
A further advantage of the assembly of the present invention is that it provides a specimen collection container which is universally compatible with various clinical equipment and instrumentation.
The assembly of the present invention may be easily handled by equipment configured to handle standard-sized blood collection tubes having standard external dimensions.
Most notably, is that the assembly of the present invention provides a blood collection container having full draw external dimensions but with a reduced internal volume as compared to standard-sized full draw blood collection tubes or standard-sized partial draw blood collection tubes.
Standard-sized full draw blood collection containers have an outer diameter of about 13 to about 16 millimeters, a length of about 75 to about 100 millimeters and an internal volume of about 6 to about 10 millimeters.
The assembly of the present invention therefore addresses the need for a full-draw low-volume blood collection container assembly that presents the external dimensions of a standard-sized blood collection tube.
The assembly of the present invention may be used to reliably collect small samples of blood or biological fluids and to maintain the integrity of the samples during storage and transport as compared to using standard-sized blood collection tubes. In addition, the assembly of the present invention can also be accommodated by standard-sized blood collection, transportation, storage, and diagnostic equipment. Furthermore, the assembly of the present invention may be used to reliably collect small samples of blood or biological fluids without being under partial pressure.
The assembly of the present invention is also compatible with existing instrumentation, labels, and bar code readers and obviates the need for new instrumentation and handling devices or procedures that would be required for smaller or varying sized tubes or tubes with flat planar bottoms.